1. Field of the Invention
The present invention relates to a maintenance support method, storage medium, and maintenance support apparatus which support maintenance of devices.
2. Description of the Related Art
TBM (Time Based Maintenance) is a maintenance diagnosis method for a device (e.g., an electric device) or equipment (e.g., a plant). In TBM, maintenance is done periodically in accordance with a check period determined for each device type independently of the device installation environment or the degree of degradation.
As an advantage of TBM, the maintenance plan is easy to determine. For example, a device or equipment manufacturer sets a maintenance period for each product it supplies. The manufacturer guarantees for users to ensure replacement parts or undertake maintenance after the supply time until the maintenance period ends.
The maintenance period is determined as a form of a predetermined period from the manufacture of the device or equipment or a predetermined period from stop of the manufacture of the model. The maintenance period is determined on the basis of the replacement part suppliable period or maintenance personnel workable period.
In TBM, check is done even when the device installation environment is good, and the degree of degradation is low. Hence, TBM is disadvantageous because it wastefully decreases the utilization of the device and increases the maintenance cost.
As other drawbacks of TBM, if the device installation environment is worse than expected, and the materials or parts easily degrade, the check period is too long, and failures may frequently occur.
Because of these disadvantages, applying TBM unconditionally for each device type is not always preferable.
The number of deteriorating devices or equipment is increasing recently. The users of devices and equipment want their operation costs to minimize.
A method of optimizing maintenance is CBM (Condition Based Maintenance). In CBM, the user of each device confirms the operation state or degree of degradation. The check period or check items are selected by the user of each device, thereby optimizing maintenance.
A method of minimizing the operation cost of the life cycle of each device is RBM (Risk Based Maintenance). In RBM, the operation cost of the life cycle of each device is minimized in consideration of tradeoff between the operation risk and the maintenance cost of the device.
The user of a device tries to optimize the maintenance method by using CBM or RBM. As a result, the number of times of maintenance is decreased, or the maintenance period is extended. Accordingly, the life cycle cost is decreased, and the reliability of the device or equipment is maintained.
Reference 1 (Jpn. Pat. Appln. KOKAI Publication No. 2002-73155) discloses a technique to allow a user to execute maintenance management corresponding to the remaining life. A plant operational limit is obtained such that it does not exceed a plant risk estimate value obtained by multiplying a fracture probability by a weight coefficient. In addition, a plant risk operation estimate value is obtained from prediction of the current remaining life and prospective remaining life.
Reference 2 (Jpn. Pat. Appln. KOKAI Publication No. 2002-123314) discloses a technique which quantitatively evaluates the risk of a maintenance portion on the basis of the antipersonnel risk, function loss risk, and environmental risk, calculates the reconstruction cost and the loss in case of failure, thereby avoiding excessive maintenance.
Reference 3 (Jpn. Pat. Appln. KOKAI Publication No. 11-119823) discloses a technique which associates failure events and failure factors on a matrix to implement accurate failure diagnosis.
The above-described maintenance support methods aim at optimizing the maintenance method. However, no concrete optimization method has been established yet.
In addition, the present states of the techniques described in references 1 to 3 are as follows.
The technique of reference 1 executes maintenance management corresponding to the remaining life. In the technique of reference 1, however, the maintenance period is not optimized.
The technique of reference 2 avoids excessive maintenance. With the technique of reference 2, basically, assessments at planning are obtained. For optimization of the maintenance method, however, reference 2 only describes an outline of reappraisal of the maintenance method and period (S10). In the technique of reference 2, the degradation by a secular change is analyzed. However, no detailed description has been made about analysis of failures except the secular change in the technique of reference 2.
The technique of reference 3 implements accurate failure diagnosis. However, the technique of reference 3 cannot optimize the maintenance period.